(1) Field of the Invention
The present invention relates to a liquid crystal display.
(2) Description of the Related Art
A liquid crystal display (“LCD”), one of the most extensively used flat panel display devices, typically includes two substrates having field-generating electrodes (such as pixel and common electrodes) mounted thereon, and a liquid crystal layer sandwiched between the substrates. The LCD generates an electric field in the liquid crystal layer by applying voltages to the field-generating electrodes, and aligns the liquid crystal molecules of the liquid crystal layer to control the polarization of light incident thereto (e.g., from a “backlight”), thereby displaying the desired images.
In a vertically aligned (“VA”) mode LCD, the directions of liquid crystal molecules are aligned vertical to the upper and lower panels (substrates) while no electric field is applied, and gives a high contrast ratio and a wide reference viewing angle. The reference viewing angle refers to a viewing angle with a contrast ratio of 1:10, or an inter-gray luminance inversion limit angle.
In the VA mode LCD, cutouts or protrusions may be formed at the field-generating electrodes to realize a wide viewing angle. As the direction of the liquid crystal molecules to be inclined is determined by the cutouts or protrusions, the inclination directions of the liquid crystal molecules can be diversified, thereby widening the reference viewing angle.
However, the VA mode LCD provides poor visibility at the lateral sides thereof, as compared to the visibility at the front side thereof. For example, in a patterned vertically aligned (PVA) mode LCD having cutouts, the luminance thereof is heightened as it comes to the lateral side thereof, and in a serious case, the luminance difference between the high grays is eliminated so that the display image may appear to be distorted.
In order to enhance the lateral side visibility, it has been proposed that a pixel controlled by one data (e.g., one color pixel) should be divided into two sub-pixels, which are capacitor-combined with each other. A voltage is directly applied to one of the sub-pixels, and a voltage drop is caused at the other sub-pixel due to the capacitor combination. In this way, the two sub-pixels are differentiated in voltage from each other and have different light transmittances.
However, with such a method, the transmittances of the two sub-pixels cannot be directly and correctly controlled to the desired level, and in particular, the light transmittance is differentiated for the respective color. The voltages cannot be differently adjusted with respect to the respective colors. Furthermore, the aperture ratio is deteriorated due to the addition of a conductor for a capacitor combination, and the light transmittance is reduced due to the capacitor combination-induced voltage drop.